Editing X-bar theory (section)

== Hierarchical structure ==
The PSR has the shortcoming of being incapable of capturing sentence ambiguities.
* I saw a man with binoculars.<ref name="binos">{{Cite web |author= |url=https://www.bu.edu/linguistics/ug/course/lx522-f05/lx522/archives/16.html|title=Syntax I|website= |publisher= |date= |accessdate=2021-10-23}}</ref>
This sentence is ambiguous between the reading ''I saw a man, using binoculars'', in which ''with binoculars'' modifies the VP, and the reading ''I saw a man who had binoculars'', in which the PP modifies the NP.<ref name="binos" /> Under the PSR model, the sentence above is subject to the following two parsing rules.
* S → NP VP
* VP → V NP PP
The sentence's structure under these PSRs would be as in Figure 13.

[[File:The_PSR_structure_of_"I_saw_a_man_with_binoculars".png|thumb|none|500px|Figure 13]]

It is obvious that this structure fails to capture the NP modification reading because [<sub>PP</sub> with binoculars] modifies the VP no matter how one tries to illustrate the structure. The X-bar theory, however, successfully captures the ambiguity as demonstrated in the configurations in Figure 14 and 15 below, because it assumes hierarchical structures in accordance with the binarity principle.

{{multiple image
|align=left
|total_width = 800
|image1=The_X-bar_structure_of_"I_saw_a_man_with_binoculars"1.png
|caption1=Figure14
|image2=The_X-bar_structure_of_"I_saw_a_man_with_binoculars"2-revised.png
|caption2=Figure15
}}{{-}}

Thus, the X-bar theory resolves the fourth issue mentioned in {{Section link||Background}} as well. There is always a unilateral relation from syntax to semantics (never from semantics to syntax) in any version of [[generative grammar]] because syntactic computation starts from the [[lexicon]], then continues into the syntax, then into [[Logical form (linguistics)|Logical Form]] (LF) at which meanings are computed. This is so under any of [[Standard Theory]] (Chomsky, 1965<ref name="C65" />), [[Extended standard theory|Extended Standard Theory]] (Chomsky, 1972<ref name="C72">{{Cite book |last=Chomsky|first=Noam|authorlink= |title=Studies on Semantics in Generative Grammar|publisher=Mouton|location=The Hague|language= |year=1972|page= |id= |isbn= |quote= }}</ref>), and [[Revised extended standard theory|Revised Extended Standard Theory]] (Chomsky, 1981<ref name="C81" />).